U.S. patent number 7,218,281 [Application Number 11/173,187] was granted by the patent office on 2007-05-15 for artificial impedance structure.
This patent grant is currently assigned to HRL Laboratories, LLC. Invention is credited to Joseph S. Colburn, Bryan Ho Lim Fong, Matthew W. Ganz, Mark F. Gyure, Jonathan J. Lynch, John Ottusch, Daniel F. Sievenpiper, John L. Visher.
United States Patent |
7,218,281 |
Sievenpiper , et
al. |
May 15, 2007 |
Artificial impedance structure
Abstract
A method for guiding waves over objects, a method for improving
a performance of an antenna, and a method for improving a
performance of a radar are disclosed. The methods disclosed teach
how an impedance structure can be used to guide waves over
objects.
Inventors: |
Sievenpiper; Daniel F. (Santa
Monica, CA), Colburn; Joseph S. (Malibu, CA), Fong; Bryan
Ho Lim (Los Angeles, CA), Ganz; Matthew W. (Marina del
Rey, CA), Gyure; Mark F. (Oak Park, CA), Lynch; Jonathan
J. (Oxnard, CA), Ottusch; John (Malibu, CA), Visher;
John L. (Malibu, CA) |
Assignee: |
HRL Laboratories, LLC (Malibu,
CA)
|
Family
ID: |
37588801 |
Appl.
No.: |
11/173,187 |
Filed: |
July 1, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070001909 A1 |
Jan 4, 2007 |
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Current U.S.
Class: |
343/700MS;
343/909 |
Current CPC
Class: |
H01Q
15/008 (20130101) |
Current International
Class: |
H01Q
1/38 (20060101) |
Field of
Search: |
;343/700,909,700MS |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Checcacci, V., et al., "Holographic Antennas", IEEE Transactions on
Antennas and Propagation, vol. 18, No. 6, pp. 811-813, Nov. 1970.
cited by other .
Fathy, A.E., et al., "Silicon-Based Reconfigurable
Antennas--Concepts, Analysis, Implementation and Feasibility", IEEE
Transactions on Microwave Theory and Techniques, vol. 51, No. 6,
pp. 1650-1661, Jun. 2003. cited by other .
King, R., et al., "The Synthesis of Surface Reactance Using an
Artificial Dielectric", IEEE Transactions on Antennas and
Propagation, vol. 31, No. 3, pp. 471-476, May 1993. cited by other
.
Levis, K., et al., "Ka-Band Dipole Holographic Antennas", IEEE
Proceedings of Microwaves, Antennas and Propagation, vol. 148, No.
2, pp. 129-132, Apr. 2001. cited by other .
Mitra, R., et al., Techniques for Analyzing Frequency Selective
Surfaces--A Review, Proceedings of the IEEE, vol. 76, No. 12, pp.
1593-1615, Dec. 1988. cited by other .
Oliner, A., et al., "Guided waves on sinusoidally-modulated
reactance surfaces", IEEE Transactions on Antennas and Propagation,
vol. 7, No. 5, pp. 201-208, Dec. 1959. cited by other .
Pease, R., "Radiation from Modulated Surface Wave Structures II"
IRE International Convention Record, vol. 5, pp. 161-165, Mar.
1957. cited by other .
Sazonov, D.M., "Computer Aided Design of Holographic Antennas and
Propagation", IEEE International Symposium of the Antennas and the
Propagation Society 1999, vol. 2, pp. 738-741, Jul. 1999. cited by
other .
Sievenpiper, D., et al., "High-Impedance Electromagnetic Surfaces
with a Forbidden Frequency Band", IEEE Transactions on Microwave
Theory and Techniques, vol. 47, No. 11, pp. 2059-2074, Nov. 1999.
cited by other .
Thomas, A., et al., "Radiation from Modulated Surface Wave
Structures I", IRE International Convention Record, vol. 5, pp.
153-160, Mar. 1957. cited by other.
|
Primary Examiner: Nguyen; Hoang V.
Assistant Examiner: Duong; Dieu Hien
Attorney, Agent or Firm: Ladas & Parry
Claims
What is claimed is:
1. A method for guiding waves over the surface of an object, said
method comprising: providing an impedance structure designed to
guide an electromagnetic wave, the impedance structure having: a
dielectric layer having generally opposed first and second
surfaces; a conductive layer disposed on the first surface; and a
plurality of conductive structures disposed on the second surface
to provide a preselected impedance profile along the second
surface; covering said object with said impedance structure,
wherein said impedance structure guides said electromagnetic wave
over the surface of said object.
2. The method of claim 1, wherein said electromagnetic wave is an
incoming plane wave or a radiation pattern of an antenna.
3. The method of claim 1, wherein said electromagnetic wave is
guided by said impedance structure to a preselected location.
4. The method of claim 1, wherein said electromagnetic wave is
guided by said impedance structure away from a preselected
location.
5. The method of claim 1, wherein said impedance structure is a
printed circuit board.
6. A method for altering performance of an antenna, said method
comprising: providing an impedance structure designed to guide an
electromagnetic wave, the impedance structure having: a dielectric
layer having generally opposed first and second surfaces; a
conductive layer disposed on the first surface; and a plurality of
conductive structures disposed on the second surface to provide a
preselected impedance profile along the second surface; covering a
surface interfering with performance of an antenna with said
impedance structure, wherein said impedance structure guides
electromagnetic waves generated by said antenna over said
surface.
7. The method of claim 6, wherein at least a portion of said
electromagnetic waves generated by said antenna are radiated by
said impedance structure.
8. The method of claim 7, wherein electromagnetic waves radiated by
said impedance structure are radiated at a preselected
location.
9. The method of claim 7, wherein electromagnetic waves radiated by
said impedance structure are radiated away from a preselected
location.
10. A method for improving performance of a radar, said method
comprising: providing an impedance structure designed to guide
electromagnetic waves, the impedance structure having: a dielectric
layer having generally opposed first and second surfaces; a
conductive layer disposed on the first surface; and a plurality of
conductive structures disposed on the second surface to provide a
preselected impedance profile along the second surface; covering a
surface, blocking said radar, with said impedance structure,
wherein said impedance structure guides and radiates
electromagnetic waves over said surface, wherein said impedance
structure guides and radiates incoming electromagnetic waves over
said surface to said radar.
11. The method of claim 10, wherein said electromagnetic waves are
generated by said radar.
12. The method of claim 1, wherein the preselected impedance
profile is non-uniform along the second surface.
13. The method of claim 6, wherein the preselected impedance
profile is non-uniform along the second surface.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This application is related to U.S. application Ser. No.
11/173,182, titled "Artificial Impedance Structures," filed on Jul.
1, 2005, which is incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
The present invention relates to artificial impedance structures.
More particularly, the present invention relates to propagating
electromagnetic waves around solid objects using artificial
impedance structures.
BACKGROUND
A common problem for antenna designers is creating antennas that
are able to radiate energy at angles that are shadowed. For
example, in Prior Art, a monopole antenna 10 on a conducting
cylinder 20, as shown in FIGS. 1a and 1b, does not radiate energy
below line 3 because the external surface of the cylinder 20 that
is below line 3 is shadowed from the monopole antenna 10. FIG 1c
shows the radiation pattern 22 produced by the cylinder 20 in FIGS.
1a and 1b.
PRIOR ART
The prior art consists of three main categories: (1) holographic
antennas, (2) frequency selective surfaces and other artificial
reactance surfaces, and (3) surface guiding by modulated dielectric
or impedance layers.
Example of prior art directed to artificial antennas includes: 1.
P. Checcacci, V. Russo, A. Scheggi, "Holographic Antennas", IEEE
Transactions on Antennas and Propagation, vol. 18, no. 6, pp. 811
813, November 1970; 2. D. M. Sazonov, "Computer Aided Design of
Holographic Antennas", IEEE International Symposium of the Antennas
and Propagation Society 1999, vol. 2, pp. 738 741, July 1999; 3. K.
Levis, A. Ittipiboon, A. Petosa, L. Roy, P. Berini, "Ka-Band Dipole
Holographic Antennas", IEE Proceedings of Microwaves, Antennas and
Propagation, vol. 148, no. 2, pp. 129 132, April 2001.
Example of prior art directed to frequency selective surfaces and
other artificial reactance surfaces includes: 1. R. King, D. Thiel,
K. Park, "The Synthesis of Surface Reactance Using an Artificial
Dielectric", IEEE Transactions on Antennas and Propagation, vol.
31, no. 3, pp. 471 476, May, 1983; 2. R. Mittra, C. H. Chan, T.
Cwik, "Techniques for Analyzing Frequency Selective Surfaces 13 A
Review", Proceedings of the IEEE, vol. 76, no. 12, pp. 1593 1615,
December 1988; 3. D. Sievenpiper, L. Zhang, R. Broas, N.
Alexopolous, E. Yablonovitch, "High-Impedance Electromagnetic
Surfaces with a Forbidden Frequency Band", IEEE Transactions on
Microwave Theory and Techniques, vol. 47, no. 11, pp. 2059 2074,
November 1999.
Example of prior art directed to surface guiding by modulated
dielectric or impedance layers includes: 1. A. Thomas, F. Zucker,
"Radiation from Modulated Surface Wave Structures I", IRE
International Convention Record, vol. 5, pp. 153 160, March 1957;
2. R. Pease, "Radiation from Modulated Surface Wave Structures II",
IRE International Convention Record, vol. 5, pp. 161 165, March
1957; 3. A. Oliner, A. Hessel, "Guided waves on
sinusoidally-modulated reactance surfaces", IEEE Transactions on
Antennas and Propagation, vol. 7, no. 5, pp. 201 208, December
1959.
Example of prior art directed to this general area also includes:
1. T. Q. Ho, J. C. Logan, J. W. Rocway "Frequency Selective Surface
Integrated Antenna System", U.S. Pat. No. 5,917,458, Sep. 8, 1995;
2. A. E. Fathy, A. Rosen, H. S. Owen, f. McGinty, D. J. McGee, G.
C. Taylor, R. Amantea, P. K. Swain, S. M. Perlow, M. ElSherbiny,
"Silicon-Based Reconfigurable Antennas--Concepts, Analysis,
Implementation and Feasibility", IEEE Transactions on Microwave
Theory and Techniques, vol. 51, no. 6, pp. 1650 1661, June
2003.
BRIEF DESCRIPTION OF THE FIGS.
FIGS. 1a and 1b relate to Prior Art and depict a monopole antenna
on a conducting cylinder, PRIOR ART;
FIG. 1c relates to Prior Art and depicts a low gain radiation
patter generated by the conducting cylinder in FIGS. 1a and 1b;
FIG. 2 depicts an artificial impedance structure;
FIGS. 3a 3b depict a monopole antenna on a cylinder covered by a
artificial impedance structure in accordance with the present
disclosure;
FIG. 3c depicts a high gain radiation patter generated by a
cylinder in FIGS. 3a and 3b in accordance with the present
disclosure;
FIG. 4a depicts a tail of an airplane covered by an artificial
impedance structure in accordance with the present disclosure;
FIG. 4b depicts an engine of an airplane covered by an artificial
impedance structure in accordance with the present disclosure;
FIG. 5a depicts an offensive device being affected by jamming
signals; and
FIG. 5b depicts an offensive device covered by an artificial
impedance structure in accordance with the present disclosure.
In the following description, like reference numbers are used to
identify like elements. Furthermore, the drawings are intended to
illustrate major features of exemplary embodiments in a
diagrammatic manner. The drawings are not intended to depict every
feature of every implementation nor relative dimensions of the
depicted elements, and are not drawn to scale.
DETAILED DESCRIPTION
According to the present disclosure, artificial impedance
structures may be placed over different surfaces to provide
scattering or guiding properties desired by the antenna
designer.
The artificial impedance structure may be designed to guide and
radiate energy from the electromagnetic waves to produce any
arbitrary radiation pattern. See, for example, a related
application U.S. application Ser. No. 11/173,182, filed on Jul. 1,
2005, "Artificial Impedance Structures," which is incorporated
herein by reference in its entirety.
Referring to FIG. 2, an artificial impedance structure 25 can be
used to design antennas on curved shapes and to have radiation
properties that would ordinarily be impossible. The artificial
impedance structure 25 may contain an artificial impedance surface
30 that comprises conductive structures 40 printed on a grounded
dielectric layer 35 that is thinner than the wavelength of
operation.
The artificial impedance structure 25 may be applied to solid
objects to guide waves around those objects. Because the methods
described here can be used to transform one wave into another
through surface wave coupling, by engineering the scattering
properties of the surface, the same concept can be used if the
source wave is an incoming plane wave or the radiation pattern of a
nearby antenna. The artificial impedance structure 25 can be used
to fill in nulls that would otherwise be created by the vehicle
structure on which the antenna is mounted. The artificial impedance
structure 25 can also be used to make better omnidirectional
antennas that are not affected by the local environment. In one
exemplary embodiment, the artificial impedance structure 25 may,
for example, be built as a printed circuit board to be wrapped
around an object that may be interfering the performance of an
antenna.
Referring to FIGS. 3a and 3b, the artificial impedance structure 25
was placed over a cylinder 60 to enable a monopole antenna 70
disposed on the cylinder 60 to produce a narrow beam on the
opposite side of the cylinder 60, toward a direction that is
otherwise shadowed. The monopole antenna 70 generates surface
currents 80 that propagate along the artificial impedance structure
25 and around the cylinder 60. The artificial impedance structure
25 was designed using the interference pattern formed by the
surface currents, and a plane wave at 135 degrees on the opposite
side of the cylinder 60. The radiation pattern 24 in FIG. 3c of the
artificial impedance structure 25 disposed on the cylinder 60
showed a narrow beam at 135 degrees.
The artificial impedance structure may also be used to guide
incoming plane waves around a solid object. For example, the
artificial impedance structure may make portions of an airplane
transparent to radiation for greater radar scan range. Referring to
FIG. 4a, a tail 91 of an airplane 92 may be covered by an
artificial impedance structure 95 to allow the radar 93 to see
through the tail 91. Referring to FIG. 4b, an engine 101 of an
airplane 102 may be covered by an artificial impedance structure
105 to allow the radar 103 to see through the engine 101. The waves
94 and 104 do not actually pass through the tail 91 and the engine
101, respectively, but are guided around the tail 91 and the engine
101 by the artificial impedance structure 95 and 101, respectively,
and re-radiate from the other side.
Using the concepts described above, an artificial impedance
structure may also be designed and used to suppress certain
incoming electromagnetic waves from propagating around a solid
object. Referring to FIG. 5a, a GPS (global position system) guided
offensive device 110 is susceptible to jammer signals 112 coming
from the ground because the surface of the offensive device 110 may
propagate the jammer signals 112 to the GPS receiver 115. Referring
to FIG. 5b, an artificial impedance structure 120 may be placed on
the portion of the offensive device 110 surrounding the GPS
receiver 115. The artificial impedance designed to only propagate
radiation from above the horizon thus making the device 110 more
resistant to jammers. The device 110 may be an offensive
device.
The foregoing detailed description of exemplary and preferred
embodiments is presented for purposes of illustration and
disclosure in accordance with the requirements of the law. It is
not intended to be exhaustive nor to limit the invention to the
precise form(s) described, but only to enable others skilled in the
art to understand how the invention may be suited for a particular
use or implementation. The possibility of modifications and
variations will be apparent to practitioners skilled in the art. No
limitation is intended by the description of exemplary embodiments
which may have included tolerances, feature dimensions, specific
operating conditions, engineering specifications, or the like, and
which may vary between implementations or with changes to the state
of the art, and no limitation should be implied therefrom.
Applicant has made this disclosure with respect to the current
state of the art, but also contemplates advancements and that
adaptations in the future may take into consideration of those
advancements, namely in accordance with the then current state of
the art. It is intended that the scope of the invention be defined
by the Claims as written and equivalents as applicable. Reference
to a claim element in the singular is not intended to mean "one and
only one" unless explicitly so stated. Moreover, no element,
component, nor method or process step in this disclosure is
intended to be dedicated to the public regardless of whether the
element, component, or step is explicitly recited in the claims. No
claim element herein is to be construed under the provisions of 35
U.S.C. Sec. 112, sixth paragraph, unless the element is expressly
recited using the phrase "means for . . . " and no method or
process step herein is to be construed under those provisions
unless the step, or steps, are expressly recited using the phrase
"step(s) for . . . . "
* * * * *